The present invention relates to a linear motion device. Linear motion devices of that type are known, e.g., as bearing rail guides or roller rail guides, in which case the first assembly is the guide carriage, and the second assembly is the guide rail. However, the present invention is also usable in a linear module, in which a linear guide having an assigned drive device is integrated to form one assembly.
JP 64-12129 A makes known a linear motion device in the form of a roller rail guide. According to FIGS. 1a and 3a of JP 64-12129 A, the linear motion device includes a first assembly in the form of a guide carriage 2, and a second assembly in the form of a guide rail 5, which are linearly movable relative to one another. A total of four first rolling surfaces 15 is provided on the first assembly, each of which is opposite a second rolling surface 11a; 11b on the second assembly. A row of roller-shaped rolling elements that may circulate endlessly in the first assembly is situated between the aforementioned rolling surfaces. For this purpose, a total of four return passages that are parallel to the first rolling surfaces is provided in the first assembly. The return passages are connected via a curved deflection passage such that rolling elements are transferred. The deflection passage and the return passage are each provided in a deflection assembly that may be installed as a whole on first body 16, the deflection assembly being accommodated in bores 14 of the body.
The deflection assembly is depicted in greater detail in FIG. 3b of JP 64-12129 A. It includes two deflection parts 20u; 20l which are separated from one another in a parting plane that extends through the midpoint trajectory of the circulating rolling elements, and so each deflection part is designed in the shape of a half shell. Each deflection part includes a first section 1 in which curved deflection channel 22 is provided, and a tubular second section 18 in which the return passage is provided.
In order to fasten the deflection assembly to the first body, two mutually assigned deflection parts are assembled to form one deflection assembly, the tubular section of which is slid into the assigned bore of the first body. The deflection assembly is therefore retained by the tubular section on the first body. The disadvantage of this embodiment is that a great deal of space is required in the longitudinal direction in front of and behind the first body in order to install the deflection assembly. This space is typically unavailable, in particular in linear modules.
A linear module is known, e.g., from DE 10 2006 007 067 A1. In that publication, allowances are made for the tight spaces by the fact that the deflection assembly may be fastened to the table assembly only from the bottom. Accessibility from the top is still required, however, so that the rivet pins (no. 34 in FIG. 2 of DE 10 2006 007 067 A1) may become plastically deformed in order to fasten the deflection assembly to the table. Moreover, DE 10 2006 007 067 A1 is equipped with an “open” return, in which an open return passage on the first body is covered by the deflection assembly. The result is much more noise as compared to the closed return mentioned in JP 64-12129 A since the returning rolling elements strike plastic on the deflection assembly and cause it to oscillate, thereby generating sound. The fact that the cover of the return channel is provided on the deflection assembly has the disadvantage that the latter may only be used in conjunction with a specified length of the first rolling surface. The deflection assembly may therefore not be used in different embodiments of linear motion devices that include first rolling surfaces having different lengths. The related deflection assemblies may therefore be manufactured only in small quantities and are therefore expensive. This is unfavorable in particular since the related plastic injection molding tools are very expensive, and are particularly suited for use to produce large quantities.